tire size .vs. gear ratio

[dizdak]

looked over many posts about gear ratios.. not many of them that i seen really touched on the tire sizes much.. i am installing 6" lift springs on my truck, plan to go up to a tire in the 33-35" tall range by 11 or 12 wide... current tires measure out to about 30" tall by 9" wide.. i have a 5spd and 3.55 gears, only drive the truck about once a week, and mostly use it to tow approx 9-10k lbs.. with current set up i feel i want more gear in town to get up with traffic... am thinking after i go up in tire size i will really want to run 4.11s or maybe even a 4.56 ratio... what are you guys thoughts and possibly some that run the larger tires what are your set ups tire size, gears, auto/ manual, tow heavy or no? and do you like the set up.. regear isn't gonna be cheap so want to make the best possible choice before shelling out the money..

 

[swervyjoe]

Might help you out:
http://www.rocky-road.com/calculator.html

 

[Iowa 73]

6" lift is too much for a 35" tire on a F-350. I run 35's on a non-lifted F-350.
4.10 gears are fine for me, but I don't tow anything with it.

 

[dizdak]

i figure the 6" springs will be over kill ( but i got then cheap so will run them) for a 33 definately.. but 35 shouldn't look too bad.... if i think it will then i may jump to a 37" and definately change gears..
thanks for the site info swerve...

 

[bike-maker]

35's, 4.10 gears, tow about the same amount of weight (5er).
I think this is a really good compromise. Geared a little low for towing, a little high for cruising down the freeway.
37" tires with 4.10 gears works out to be almost the same as 3.55 gears and stock size tires.

 

[Iowa 73]

If you check ebay you can get a great deal on 37" BFG military surplus tires. Those would be great w/ 6" lift. If you have to re-gear anyways, you may as well go to 4.56 or 4.88.

 

[riotwarrior]

looked over many posts about gear ratios.. not many of them that i seen really touched on the tire sizes much.. i am installing 6" lift springs on my truck, plan to go up to a tire in the 33-35" tall range by 11 or 12 wide... current tires measure out to about 30" tall by 9" wide.. i have a 5spd and 3.55 gears, only drive the truck about once a week, and mostly use it to tow approx 9-10k lbs.. with current set up i feel i want more gear in town to get up with traffic... am thinking after i go up in tire size i will really want to run 4.11s or maybe even a 4.56 ratio... what are you guys thoughts and possibly some that run the larger tires what are your set ups tire size, gears, auto/ manual, tow heavy or no? and do you like the set up.. regear isn't gonna be cheap so want to make the best possible choice before shelling out the money..

For starters here, this should help....NOW REMEMBER TO USE 4TH for the calculations as 5th is OD! This chart is based on 4th as 1 to 1 ratio...so you can go deeper meaning lower gears as you have an OD5th

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Now I run 4;10's and 34's and have no problem 255x85x16's so they are not as wide as your goal but they are a good height. I've a stock F350 and no clearance issues what so ever.

six inches of lift and even wider tyres would look stupid on my truck if I kept the same height. To me it's about how it performs LONG before how it looks. So if you have 6" lift 37's and say 4:88 you may just be near spot on!

JM2CW

Al

 

[mblaney]

Why would you lift and put oversize tires on a primarily towing vehicle? I would think that stock configuration would be the optimum and safest setup? I know this doesn't answer the question but...

 

[dizdak]

thanks, i was looking for that gear calculator earlier.. i wasn't thinking the 6" springs would let me clear larger than 35s but is seems it will.. i actually like the 37" tire idea better, i pull my play truck and trailer off road in sandy/ muddy areas many times before i unload so the larger more agressive tire should help me not work the truck as hard, my current tires cower at the sight of loose sand!!! from the looks of that chart if i do end up with 37s, the 4.56 will be the better empty gear and 4.88s will be better towing gear..i would rather have a little more when towing so the 4.88s are tempting.. will definately be adding a set of ladder bars to the rear end when this is done..

 

[dizdak]

mblaney- to answer your question there is no real reason why i want a lift and larger tires.. mostly for looks, and i just can't leave stuff alone... big pull truck, bigger play truck it all just goes together down south here i guess..

 

[riotwarrior]

thanks, i was looking for that gear calculator earlier.. i wasn't thinking the 6" springs would let me clear larger than 35s but is seems it will.. i actually like the 37" tire idea better, i pull my play truck and trailer off road in sandy/ muddy areas many times before i unload so the larger more agressive tire should help me not work the truck as hard, my current tires cower at the sight of loose sand!!! from the looks of that chart if i do end up with 37s, the 4.56 will be the better empty gear and 4.88s will be better towing gear..i would rather have a little more when towing so the 4.88s are tempting.. will definately be adding a set of ladder bars to the rear end when this is done..

Remember what I mentioned that gear calculator is for a 1 to 1 hi gear, so 4:88's would work well with the 5sp trans! You have OD and thus instead of 2880 RPM you'll be down around 2150 or there bouts....So do all your calculations based on 1 to 1 and factor OD in for later...You could even go 5:13's ...

Just sayin

 

[dizdak]

thanks riotwarrior... i am likeing the idea of 4.88s and some 37s when this is all said and done.. hope to have the springs on tonight and have it set back on the ground... then i can see just how much tire room i am looking at..

 

[mblaney]

mblaney- to answer your question there is no real reason why i want a lift and larger tires.. mostly for looks, and i just can't leave stuff alone... big pull truck, bigger play truck it all just goes together down south here i guess..

Just don't make your tow truck taller than the one you are towing (the one in your avatar?)

 

[dizdak]

oh no that won't happen, the yota is almost at 9' from ground to top of roof!!

 

[bobracing]

Best gear calculator I've found.

http://www.grimmjeeper.com/gears.html

You'll also need to think about brakes when going to the larger tires. A hydroboost might be in the near future plans if big tires are.
Actual tire size might be another thing to consider before changing gears. The 37" MTRs measure out at 36" actually, where some of the Swamper's bias ply might measure a little tall.